Abstract:Plasma physical vapor deposition (PS-PVD) generally adopts the process of high helium flow rate and high gun input power to obtain the thermal barrier coating with columnar/quasi-columnar structures and excellent performance of column/quasi-column structure. In this study, the energy variation of the deposition position corresponding to the center of the plasma jet and its effect on the microstructure of the coating were studied under the condition of low nitrogen flow rate and low gun input power. The results show that under the condition of 90 L/min plasma gas flow rate, the Ar/He volume ratio is adjusted from 1︰2 to 2︰1, and the helium flow rate is reduced, and the quasi-columnar structure coating can be obtained. Under the condition of Ar/He volume ratio 1︰1, the jet energy is the highest. In this case, the effect of He on the plasma jet beam absorption is weakened, the thickness of the columnar crystals is reduced, the condensation particles between the columnar crystals are increased, and the deposition efficiency of the coating is significantly reduced. When the total gas flow rate is 120 L/min and the Ar/He volume ratio is 2︰1, the dense coating structure dominated by liquid phase deposition can be obtained. Combined with the spectral analysis results of characteristic peaks of each element, the intensity of Zr Ⅰ characteristic peak is the highest when Ar/He volume ratio is 1︰1, and then with the decrease of Ar/He volume ratio, the constraint of He on the gas phase of the plasma jet and the comprehensive influence of He on the energy field of the plasma jet determine the microstructure characteristics of the coating.